Low-Frequency Noise Characterization of Ultra-shallow Gate N-channel Junction Field Effect Transistors

A recently developed technique for ultra shallow pn junction formation has been applied for the fabrication of ringgate n-channel junction field effect devices (JFET) devices. Several different geometries, gate formation parameters and channel doping profiles have been realized and characterized with respect to I-V and C-V characteristics both on wafer and after packaging. Low-frequency noise measurements have been performed on packaged devices by mean of a cross-correlation scheme. Data have been compared both with that of similar devices fabricated in a standard process and with simulations results. The devices show good DC performance, and the transconductance values achieved, with respect of the channel dimensions, are notably high. No G-R noise was detected, but the devices yielded a high flicker noise component. This phenomenon is shown to be neither correlated to the device area nor to incidental trapping levels at the junction interface. It is therefore assumed that perimeter effects are decisive for the enhancement of the 1/f spectrum.